Local-pitch identification accuracy depending on the trajectory of frequency-modulated tones

Abstract

Local-pitch identification accuracies were analyzed for frequency-modulated (FM) tones. The problem was whether every portion of a continuous sound was perceived at the same accuracy or not. Psychophysical experiments revealed that the local-pitch identification accuracies were significantly different among the nodes of continuous FM tones. Also, the accuracies were dependent on the frequency trajectory shape. The stimuli were two types of piecewise-linear FM tones of up-down-up and down-up-down glide sequences. Each tone included four nodes; the initial, two intermediate points, and the final. The duration of each linear glide was 100 ms. The frequency range was between 1000 and 1500 Hz. A pair of FM tone was presented with one-second interval. The frequency was shifted up or down at one of the nodes in either of the tones. The shift amounts were 0%, 4%, and 8%. The subjects were requested to answer whether two pitch sequences were the same or different. The pitch identification accuracy was low at the initial for both types of FM tones. The accuracy at the final was highest for the up-down-up tone. The intermediate high frequency node showed the highest accuracy for the down-up-down tone. These results indicated that the local-pitch identification accuracies were trajectorydependent.